Mitigation Strategies to Protect Water Quality

Considerable resources are available to help almond growers meet requirements to prevent agricultural inputs from being discharged into surface water.

The Coalition for Urban/Rural Environmental Stewardship, with support from the Almond Board of California, publishes the Watershed Coalition News, which keeps almonds growers informed on regulatory issues affecting irrigation runoff, and provides Best Management Practices (BMP) guidelines for preventing agricultural inputs from being discharged in runoff.

Runoff Mitigation
Here are some ways growers can help prevent water runoff from contaminating surface water:

• Vegetated buffer ditches or strips.  A wide, shallow channel that slows the flow of irrigation or storm water drainage will allow sediment to settle rather than being transported into a waterway.  Vegetated ditches must be planted, ideally in the fall, in order to be effective.
• Settling (holding) pond.  If irrigation or storm water runoff is high in sediment, a settling pond may be needed to remove some portion of the suspended silt before flowing through the ditch.
• Precision irrigation.  Use microsprinklers or drip irrigation to reduce the amount of tailwater runoff.  Monitor soil moisture and schedule irrigations according to crop requirements.  For flood irrigation, create a tailwater return system that either collects and returns water for irrigation or places tailwater in a holding pond.
• Nutrient management.  For an economical and environmentally sensible fertilization program, determine tree nutrient demand and replace what is removed by the crop.  Time nutrient applications to match tree uptake to avoid having excess nutrients in the soil subject to leaching and/or runoff.
• Minimize overwatering. Runoff from agricultural operations that leaves a property may contain sediment, nutrients, chemicals, etc. and is regulated by the California State Water Code Compliance under the Irrigated Lands Conditional Program is available to growers who have runoff.   To reduce the discharge rate of a sprinkler sytem, change the size of the nozzle or the operating pressure, or change set times.  Cover crops are another way to reduce runoff by increasing the water intake rate of the orchard floor.  Using a spring tooth harrow to break up the soil surface also increases water intake.

Spray Drift Management
By calibrating spray equipment to apply accurate rates and focus the spray on the crop foliage, spray drift is reduced and less spray is applied to the ground below the tree canopy.  The reduction of spray above and below the canopy reduces the load of pesticides in storm water and irrigation runoff.  Growers should regularly check sprayer nozzles and orifices for clogging and damage, clean screens frequently, and use only potable water from a closed source. Generally the smaller the droplet size the greater the chance of drift. Also, key to reducing drift is not spraying in windy conditions. Additionally, turning the sprayer off when making turns and when near sensitive areas helps prevent spray drift.

External Links:

BMP Guidelines